Does your local MLS restrict aspect ratio? I like having the freedom to crop outside of the standard 3:2 ratio and even shoot vertical/portrait orientation. I think it's important to achieve the right composition first and foremost and that is not always landscape 3:2. If you happen to be restricted by your MLS, you might find this Lightroom preset helpful. It's a free download, and I explain how to use it in this video.
How do you handle delivering photos outside of landscape 3:2 orientation?